Objectives: We are studying the metabolic activity and fate and non-renewable macromolecules (collagen, elastin, amyloid) as well as the amount and kind of crosslinkages involved. The consequences of non- renewability and crosslinking of collagen and elastin are being evaluated in terms of its mechanical properties at a microscopic level and its dynamic mechanical properties at the ultramicroscopic level. Goals for the current year: A physiological and metabolic studies of aging in intact animals. (1) Quantitative relationship between destructive and conservative turnover of collegen, (2) Crosslinking of collagens, (3) Characterization of a new acidic structural protein from skin (proamyloid). Physical and mechanical properties of aging connective tissues. (1) Mechanical behavior of aged bone, (2) Effect of animal age upon denervated muscle; (3) Use of collagen models for determing dynamic mechanical behavior, (4) Mechanical behavior of collagenous tissues; (5) Ultrastructural studies of collagen deformation, (6) Thermodynamic studies of collagen structure by microcalorimetry. Chemical and physical studies of macromolecules. (1) Location of intermolecular crosslinks, (2) Mechanism of formation of crosslinks in elastin, (3) Non-collagenous portions of procollagen, (4) Establishment of a rapid assay system for determining the age of human collagen and (5) Synthesis and characterization of poly (LysAla3) as a model for the maturational studies of elastin.